1. Field of Invention
This invention generally relates to zoom lenses, and more particularly to compact and portable zoom lenses used in compact cameras.
2. Description of the Related Art
In general, if conventional zoom lenses are designed so as to have a power ratio of two or greater, the total lengths of their lens systems become relatively long, which prevents these zoom lenses from being adequately used in compact cameras. On the other hand, if a conventional zoom lens is designed so as to reduce its focal lengths at wide-angle end to about 28 mm, the structure of the lens system becomes too complicated, resulting in a high manufacturing cost.